Role of Oligopeptide Transport in Plant Growth and Development

肽转运是一种广泛存在的现象，例如长度为2-6个残基的肽以能量依赖性和可饱和的方式跨质膜易位。肽转运蛋白分为三个家族：ATP结合盒家族（ABC转运蛋白）、肽转运蛋白（PTR）家族（转运二肽和三肽）和最近描述的寡肽转运蛋白（OPT）家族。拟南芥基因组的完成表明，这种植物具有10倍以上的预测肽转运蛋白比其他测序的生物。例如，有52个预测的PTR家族成员和9个推定的肽转运蛋白OPT家族成员。OPT家族成员介导四肽和五肽的摄取。最近的研究结果表明，AtOPT 3：：T-DNA突变体在发育中的种子中的胚形成中有缺陷。对opt 3胚胎的检查表明，发育在8细胞阶段被阻断。总之，这些数据有力地表明，肽转运蛋白在植物生长和发育中起着非常重要的，未探索的作用。拟议的研究旨在确定每个拟南芥OPT肽转运蛋白的生理作用。这将通过检查在酵母和非洲爪蟾卵母细胞中表达的这些蛋白质的肽转运活性来完成。反向遗传学将用于获得转运蛋白功能缺陷的植物。突变体将在其生长和发育方面进行表征（例如，胚胎）表型，以及它们转运肽的能力。通过在转基因植物中表达表位标记的蛋白质来检查每种蛋白质的细胞定位。这项研究可能会导致新的信号通路或营养循环的途径，这是至关重要的正常植物生长和发育的认识。更广泛的影响：研究和教育将通过本科生，研究生和博士后助理的参与整合在项目中。通过与密苏里州大学校园内完善的项目对接，将增加代表性不足的群体对科学的参与。基础设施将通过购买所需的电生理设备来改善，这些设备将作为校园范围内的资源。分子生物化学和综合植物生物学项目共同资助该项目。

Peptide transport is a widespread phenomenon exemplified by the translocation of peptides 2-6 residues in length across the plasma membrane in an energy-dependent and saturable manner. Peptide transporters fall into three families; the ATP binding cassette family (ABC transporters), the peptide transporter (PTR) family (transporting di- and tripeptides) and the recently described oligopeptide transporter (OPT) family. Completion of the Arabidopsis genome revealed that this plant possesses 10-fold more predicted peptide transporters than other sequenced organisms. For example, there are 52 predicted members of the PTR family and 9 putative members of the OPT family of peptide transporters. The OPT family members mediate the uptake of tetra- and pentapeptides. Recent results indicated that an AtOPT3::T-DNA mutant is defective in embryo formation in the developing seed. Examination of the opt3 embryo showed that development was blocked at the 8-cell stage. Together, these data strongly suggest that peptide transporters play very important, unexplored roles in plant growth and development. The proposed research seeks to define the physiological role for each of the Arabidopsis OPT peptide transporters. This will be done by examining the peptide transport activity of these proteins expressed in yeast and in Xenopus oocytes. Reverse genetics will be used to obtain plants defective in transporter function. Mutants will be characterized with regard to their growth and developmental (e.g., embryo) phenotype, as well as their ability to transport peptides. The cellular localization of each protein will be examined by expressing epitope-tagged proteins in transgenic plants. This research may lead to the recognition of new signaling pathways or avenues of nutrient circulation, which are critical to normal plant growth and development.Broader Impact: Research and education will be integrated in the project by the involvement of undergraduates, graduate students and postdoctoral associates. Participation of under-represented groups in science will be increased by interfacing with well established programs on the University of Missouri campus. Infrastructure will be improved by the purchase of needed electrophysiology equipment, which will serve as a campus-wide resource.The Molecular Biochemistry and Integrative Plant Biology Programs jointly fund this project.